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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Investigation of light source and scattering medium related to vapor-screen flow visualization in a supersonic wind tunnel

Methods for increasing the radiant in light sheets used for vapor screen set-ups were investigated. Both high-pressure mercury arc lamps and lasers were considered. Pulsed operation of the air-cooled 1-kW lamps increased the light output but decreased reliability. An ellipsoidal mirror improved the output of the air-cooled lamps by concentrating the light but increased the complexity of the housing. Water-cooled-4-kW lamps coupled with high-aperture Fresnel lenses provided reasonable improvements over the air-cooled lamps. Fanned laser beams measurements of scattered light versus dew point made in conjunction with successful attempts to control the fluid injection. A number of smoke generators are described and test results comparing smoke and vapor screens are shown. Finally, one test included a periscope system to relay the image to a camera outside the flow.

Snow, W. L.↗
NASA NTRS1973

Epitaxial growth of III-V compounds for electroluminescent light sources

The epitaxial growth techniques used in the fabrication of III-V compound electroluminescent devices are reviewed. Both vapor and liquid phase epitaxial techniques are discussed, including the applications of these techniques to well established materials as well as newer materials. The state of the art of light-emitting devices fabricated from members of the III-V compounds and their solid solutions is also reviewed.

Chu, T. L.↗
DOE OSTI2024

Vacuum-ultraviolet light source for enhanced production of metastable krypton and xenon beams

Here, we demonstrate excitation of metastable krypton and xenon beams using a vacuum ultraviolet lamp and directly compare the performance of this method to metastable excitation based on a radio-frequency-driven plasma discharge. In our apparatus, lamp-based metastable excitation outperforms the plasma discharge across a wide range of beam flux values relevant for atom trap trace analysis (ATTA). Moreover, we do not observe significant degradation in lamp performance after over 160 h of operation. We find that lamp-based excitation is particularly advantageous at the smallest and largest beam fluxes tested, demonstrating the utility of this approach both for improving krypton ATTA and for enabling the detection of radioactive xenon isotopes using ATTA. Finally, we demonstrate an additional enhancement to lamp-based metastable excitation efficiency and stability by applying an external magnetic field.

Metastable noble gases↗
DOE OSTI2024

Time-resolved synchrotron light source X-ray detection with Low-Gain Avalanche Diodes

Low Gain Avalanche Diodes (LGADs) represent the state-of-the-art in timing measurements and will instrument future timing detectors at the High Luminosity Large Hadron Collider (HL-LHC) experiments. While conceived as a sensor for charged particles, the intrinsic gain of LGADs makes it possible to detect low energy X-rays with good energy resolution and excellent timing (tens of picoseconds). Here, using the Stanford Synchrotron Radiation Lightsource (SSRL) at SLAC, several LGADs designs were characterized with energies from 5 to 35 keV. The SSRL provides 10 ps pulsed X-ray bunches separated by 2.1 ns intervals, and with an energy dispersion (ΔE/E) of 1 X 10 -4 . LGADs fabricated by Hamamatsu Photonics (HPK) and Brookhaven National Laboratory (BNL) with different thicknesses ranging from 20 µm to 50 µm and different gain layer designs were read out a two stage fast amplification circuit and digitized with a high bandwidth, high sampling rate oscilloscope. PIN devices from HPK were characterized as well. A systematic and detailed characterization of the devices’ energy linearity, resolution and timing resolution as a function of X-ray energy was performed for different biasing voltages at room temperature

Charge multiplication↗
DOE OSTI2022

The fluctuation–dissipation measurement instrument at the Linac Coherent Light Source

The development of new modes at x-ray free electron lasers has inspired novel methods for studying fluctuations at different energies and timescales. For closely spaced x-ray pulses that can be varied on ultrafast time scales, we have constructed a pair of advanced instruments to conduct studies targeting quantum materials. We first describe a prototype instrument built to test the proof-of-principle of resonant magnetic scattering using ultrafast pulse pairs. This is followed by a description of a new endstation, the so-called fluctuation–dissipation measurement instrument, which was used to carry out studies with a fast area detector. In addition, we describe various types of diagnostics for single-shot contrast measurements, which can be used to normalize data on a pulse-by-pulse basis and calibrate pulse amplitude ratios, both of which are important for the study of fluctuations in materials. Furthermore, we present some new results using the instrument that demonstrates access to higher momentum resolution.

Assefa, T. A.↗
DOE OSTI2023

Toward streaked collective Thomson scattering measurements on an extreme ultraviolet plasma light source

Here we show through forward modeling calculations that streaked collective Thomson scattering measurements are feasible on laser-produced tin plasmas generated under conditions relevant for extreme ultraviolet lithography. Using a 532 nm probe laser beam, the feasibility of simultaneous measurements of electron plasma wave (EPW) and ion acoustic wave (IAW) spectra is investigated. Absolute photon counts for laser scattering off both waves are calculated. Probe laser electron heating and bremsstrahlung background radiation effects are accounted for. While a large spatiotemporal region can be successfully probed based on the IAW feature, only one measurement location can be accessed through the EPW as a result of the low signal to noise ratio. A portable/traveling tabletop system is proposed.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

In situ temperature synthesis and characterization of ferroelectric PZN-4.5PT nanoparticles’ thin films using synchrotron light source

Despite the excellent properties of Pb(Zn 1/3 Nb 2/3 )O 3 -4.5PbTiO 3 (PZN-4.5PT) single crystals, the greatest difficulty for their application on electronic devices is to make them to thin layers related to the difficulty to make them as ceramic materials. In this paper, we use the combined USAXS/SAXS/WAXS instrument at 9ID beamline at APS-ANL for in situ characterization of PZN-4.5PT inorganic perovskite nanoparticles thin films deposited on nanotextured silicon to understand the phase transitions and determine the observed microcrystals' structure. Here, the sample was annealed from ambient to 1000°C. The results revealed structure changes in the nanoparticles' thin films which could be explained by the new phase that can be assigned to the Pb 3 (PO 4 )2-based component. The peak at 31° indicates the presence of the rhombohedral phase perovskites assigned to the nanoparticles. WAXS characterization permitted to identification of many transitions during thermal annealing like dehydration or dihydroxylation of phosphorus gel -OH bonds and internal water.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Synchrotron light source X-ray detection with Low-Gain Avalanche Diodes

Abstract Low Gain Avalanche Diodes (LGADs) represent the state-of-the-art in timing measurements and will instrument the future Timing Detectors of ATLAS and CMS for the High-Luminosity LHC. While initially conceived as a sensor for charged particles, the intrinsic gain of LGADs makes it possible to detect low-energy X-rays with good energy resolution and excellent time resolution (tens of picoseconds). Using the Stanford Synchrotron Radiation Lightsource (SSRL) at SLAC, several LGADs designs were characterized with energies from 5 to 70 keV. The SSRL provides 10 ps pulsed X-ray bunches separated by 2 ns intervals with an energy dispersion (ΔE/E) of 10 -4 . LGADs from Hamamatsu Photonics (HPK) and Brookhaven National Laboratory (BNL) with different thicknesses ranging from 20 μm to 50 μm and different gain layer designs were read out using fast amplification boards and digitized with a high bandwidth and high sampling rate oscilloscope. PIN devices from HPK and AC-LGADs from BNL were characterized as well. A systematic and detailed characterization of the devices' energy linearity, resolution, and time resolution as a function of X-ray energy was performed for different biasing voltages at room temperature and are reported in this work. The charge collection and multiplication mechanism were simulated using Geant4 and TCAD Sentaurus, providing an important handle for interpreting the data.

Instruments & Instrumentation↗
DOE OSTI2021

NNSA Light Source Enhancements: Coupling a High Energy Laser Driver to an XFEL

NNSA has an unmet capability gap to predict how changes in material microstructure, due to aging and new manufacturing practices, can affect performance at extremes. This capability gap is the basis for the Dynamic Mesoscale Material Science Capability (DMMSC) CD-0 that was signed in 2015 [1]. Because of the delay to the MaRIE facility approach, the Tri-Lab in March 2020 proposed separate complementary investments at the APS and LCLS to address portions of the DMMSC mission need [2].

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗